In fluid systems, it is frequently necessary to utilize composite fluids which cannot be stored in the system during periods of flow stagnation. For example, liquid reaction molding systems may use glass fiber suspensions in the one of the reagents which is to be mixed. A glass fiber generally remains suspended so long as the system remains operative and the particulated fluid remains dynamic. When, however, the fluid is stagnated, as for example during system shut-down, the particulated matter tends to migrate downwardly under gravity bias and settle in the bottom portions of the fluid system. As the particulate matter accumulates, it tends to pack, and the possibility exists that redispersion will not occur when the system is started once again. The failure of the particulate matter to redisperse results in system flow obstructions.
One method of preventing particulate accumulation is to purge the fluid system of the composite fluid during system breakdown. The prior art systems have purged fluids in a variety of ways. One method of removing fluid has been to force high-pressure air through the system. Another method has been solvent purging in which a solvent is used to flush and cleanse the system of the reactive material. These methods have not been entirely satisfactory for all systems, however. For example, in the air purge method, the air has a disadvantageous tendency to channel through the liquid and leave a thick peripheral film of liquid in the lines. The solvent purge method overcomes the disadvantage of channeling but tends to contaminate the reactant it is removing. This latter disadvantage while perhaps tolerable when small amounts of fluid are to be removed, becomes significant with larger systems due to the large amount of reactants that become unusable due to contamination. The present invention alleviates the above-mentioned problems and ameliorates many of the problems encountered in the purging process. The purging fluid is recaptured and upgraded for future use in the system.